   (+ centre (* range (Math/cos (* 2 Math/PI idx (/ 1 period))))))
 
 (defn sinr
-  "Scaled, shifted (i.e. mul-add) sine fn with the frequency specified in terms of the idx (typically representing the beat).
+  "Scaled, shifted (i.e. mul-add) sine fn with the frequency specified in
+  terms of the idx (typically representing the beat).
 
   Returns a value at idx along a scaled sine fn with specified centre and
   range. The frequency is defined to be period idxs. Similar to Impromptu's

  overtone.algo.trig)

(defn cosr
  "Scaled, shifted (i.e. mul-add) cosine fn with the frequency specified in terms of the idx (typically representing the beat).

  Returns a value at idx along a scaled cosine fn with specified centre and
  range. The frequency is defined to be period idxs. Similar to Impromptu's

  (+ centre (* range (Math/sin (* 2 Math/PI idx (/ 1 period))))))

(defn tanr
  "Scaled, shifted (i.e. mul-add) tan fn with the frequency specified in
  terms of the idx (typically representing the beat).

  Returns a value at idx along a scaled tan fn with specified centre and
  range. The frequency is defined to be period idxs. Similar to Impromptu's
